Distillation of tar



NOV. 22, 1932. p MlLLER 1,888,235

DISTILLATION OF TAR 'J N L I INVNTOR 1 WWW I BY LU WAWMMYW ATTORNEYSNov. 22, 1932. 1,888,235

DISTILLATION OF TAR Filed March 14. 1 2 4 Sheets-Sheet 3 INVENTOR MMMATTORNEYS Nov. 22, 1932. 1,888,235

DI'STILLATION 0F TAR Filed March 14, 1927 4 Sheets-Sheet 4 ATTORNEYINVENTOR E, W M

Patented Nov. 22, 1932 UNITED STATES- PATENT OFFICE STUART PARKELEEMILLER, 01 TENAILY, NEW JERSEY, ASSIGNOR TO THE BARRETT COMPANY, OF NEWYORK, 11'. Y, A CORPORATION OF NEW JERSEY DISTILLATION O1 TABApplication fled 1mm 14, 1927. sum a... 125,075.

This invention relates to improvements in the distillation of tars, andparticularly to the utilization of the heat available in the gasesproduced in coal-carbonization plants, 5 such as coke ovens, to distilltar and to produce pitches and an increased proportion of oils by suchdistillation. The invention will; be described especially with referenceto its application to coke ovens.

In the ordinary operation of by-product coke ovens the gases produced bythe coking operation pass from the .individual ovens through uptakepipes and goose-necks to a collector main common to the ovens of thebattery. The gases, commonly known as .foul gases, leave the ovens athigh temperature, e. g., 600 to 700 C. or higher, and carry aconsiderable proportion of tars and oils. Ordinarily the gases arecooled as rapidly as possible by the application of sprays of ammonia,or ammonia liquor and tar, in the oose-necks and collector main, theheat in tie gases being thereby dissipated and lost. The rapid coolingcauses separation of the tar containing the heavier oils in thecollector main. Further cooling is effected in the cross-over main whichconnects the collector main to the condensing system and heavier andlighter oils is thus separated. The collected tar is commonly shippedfrom the coke-oven plant to a tar-distillation plant for distillationand separation of the oils and the production of pitches of varyingqualities. Handling losses, freight charges and distillation costs,including fuel and capital and maintenance expenses for the specialequipment required for distillation, add to the cost of production ofthe end products of thedistillation. v

It is an object of the .present invention to provide a method andapparatus which permit the distillation of tar at a coke-oven plant,utilization of the heat of the coke-oven gases for that purpose, andparticularly the production of pitches having varying characteristicsand the enrichment of the gases in oil vapors which may be condensedsubse- 50 quently for recovery of valuable oil constituents.

an additional quantity of tar carrying both According. to the presentinvention the heat of the coke-oven gases isutilized immediately afterthe gases 'leavethe coke ovens to distill tar by spraying or otherwisebringmg the tar into intimate contact with the hot coke-oven gases, forexample, in a structure connected directly to the uptake pi e from acoke oven and arranged to utilize irectly the heat of the gases issuingtherefrom. The gases are at relatively high temperature, e. g., 600 to700 0., or higher, but the temperature will drop owing to absorption ofheat therefrom b the tar which is caused to intimately min e with them.The tar is thus heated an distilled, the vapors of 'the volatile oilmingling with the coke-oven gases and passing along with them. vTheextent of the drop in temperature of the'gases depends upon the amount,nature and temperature of the tar sprayed in and the interval of contactof the tar with the gases. The tar is introduced into the gases at aplurality of levels so that the gases are. subjected in sucoessive zonesof tar sprays. The temperature drop and the amount of distillationineach zone will be regulated by the amount, kind and temperature of thetar introduced as well as by the water content of the tar.

The tar supplied at different levels in the still may be the same tar,or heavy and light tars may be supplied at'difierent levels, or oilderived from the tar can be introduced at the upper levels and heaviertars at'the lower. Preferably, the still is arranged so that the tarssupplied .at the different levelstherein and thus subjected to theheating effect of the hot coke-oven gases at the varying temperatures ofthese gases in the still can be withdrawn at the different levels sothat the ar- 4 rangement permits the production of different grades ofpitches or tars in asingle operation. Thus, for example, heavy tar orpitch can be supplied at the lower levels and being subjected to thehighest available tempera-- ture therein can be distilled to produceheave ier pitches whereas thelower temperature at the upper levels canbe utilihed to partially distill tars or to dehydrate the same inpreparation for further distillation in the lower levels or in otherdistillation apparatus.

Ammonia liquor can be added in regulated amounts with the tar in case itisdesired to regulate the distillation of the gases and to hold it to adefinite limit..

In carrying out the invention the construction of the coke oven and ofits by-product recovery system may remain unchanged except in respect tothe provision of one or more stills as hereinbefore described. Thesestills may be connected to the usual uptake pipes of the ovens and tothe usual collector main so that the gases and vapors resulting from thedistillation will be delivered to the collector main and may besubjected therein to cooling if desired by the use of sprays of ammonialiquor or of tar and ammonia liquor in accordance with the usualpractice. The gases and vapors from the collector main may be conductedthrough the usual crossover main in which further cooling may beefi'ected and thence delivered to the condensing system in which thevapors are condensed and the resulting oils are separated from thegases. These gases may then be passed through theusual equipmentemployed in coke-oven condensing systems to recover valuable productsleaving the fuel gases for use as such. The tar or tar and oil which mayseparate in the collector and cross-over mains can be withdrawn andsubjected in suitable decanters to separation from the ammonia liquorwhich may be returned to the collector main for further use as a coolingmedium. The separated tar or tar and oil can be returned to the stillsfor further distillation or subjected to any other suitable treatment.

While all of the ovens of a coke-oven battery may be provided withstills of the character described for the purpose of distilling tar andenriching the gases in volatile constituents oftar, the invention may beapplied also by utilizing such stills only in connection with a selectednumber of ovens. The amount of heat, available in the hot cokeoven gasesfrom a battery of coke ovens is many times that required for thedistillation of the tar produced by such a battery. Consequently, if allof the ovens are provided with stills it will be necessary to supply tarfor distillation, from sources other than the battery of coke ovens withwhich such stills are connected. In a lant where a large number ofbatteries 0 coke ovens are operated a single battery can be providedwith stills as described, and the tar produced in the entire plant canbe distilled therein.

If only a single battery is operated in the plant tar from other plantscan be distilled in order to maintain continuous operation in the mannerdescribed. Or the tar produced by the battery can be accumulated anddistilled at intervals in the manner described.

If tar from other sources than the battery is not available it will benecessary only to provide one or more stills connected to one or moreovens of the battery, the remain ing ovens being connected by means ofthe ordinary uptake pipes and goose-necks to the common collector main.In this case the battery may be operated in the usual manner, most ofthe gases being delivered directly to the collector main withoututilization of the heat therein and only the gases from the selectedovens will be utilized in the stills for the distillation of tar.

Since the gases which have been utilized for tar distillation arerelatively richer in 011 vapors than normal coke-oven gases, it

may be desirable, particularly where only a few stills areemployed inconnection with the battery, to provide a separate condensing system forthese vapors. Thus, instead of deligering the gases containing thevapors derived from distillation to the ordinary collector main, thesegases may be conducted through a separate condensing system includ-While stills of various forms and construction can be utilized for thepurpose of the invention, the preferred arrangement includes acylindrical structure arranged directly above and connected to the usualuptake pipe which may discharge the gases into the still. A baflie is'provided preferably above the end ofthe uptake pipe to prevent tar fromdescending into the coke oven. Spray nozzles are arranged at severallevels of the still and are connected by suitable pipes to a. source orsources of tar or oil under pressure suflicient to cause the tar or oilto'be atomized by the spray nozzles. Annular collectors are arrangedwithin the still beneath each of the spray nozzles so as to collect thetar or oil or the pitch formed therefrom after the hot gases have passedtherethrough.

The gases entering at the bottom of the still will be forced outwardlyby the baffle and will circulate upwardly so that the gases areintimately mingled with the sprays of tar or oil. The gases will becooled progressively while the tar or oil introduced through each spraynozzle at each successively higher level will be subjected to a lowertemperature suflicient, however, to accomplish distilla'tion or partialdistillation of the tar or oil in the still.

The extent to which the temperature of the gases will be lowered willdepend upon the height of the still, the number of tar sprays, thevolume of tar or oil introduced,

the type and temperature of the tar or oil, the amount of water in it,and the velocity of the gases through the still. If the still issufiiciently high the temperature of the gases at the top thereof may beonly high enough to dehydrate or dehydrate and distill the lighter oilsfromthe tar. The tar or oil or the pitch formed therefrom is separatelycollected at each level and can be separately withdrawn through outletpipes provided for that purpose. In this manner pitches of differentconsistency and having difierent qualities can be producedsimultaneously in the stills. The pitches produced can be recirculatedif desired through the still by introduction thereof at the same or adifierent level and thus subjected to the desired degree of heat toaccomplish the intended purpose.

The invention will be further illustrated by the following more detaileddescription in connection with the accompanying drawings which showapparatus embodying the invention and adapted for the practice of theprocess, but itis intended and will be understood that the invention isillustrated thereby and is not limited to the details of the apparatusas disclosed.

In the accompanying drawings, Fig. 1 is a plan view of a portion of acoke-oven battery embodying the invention;

Fig. 2 is an elevation thereof;

Fig. 3 is an enlarged detail in section showing the preferred structureof the still; and

Fig. 4 is a plan view of a portion of a coke oven illustrating theapplication of a separate condensing system to the stills.

The invention is of more or less general application to difierent typesand constructions of by-product coke ovens such as Semet- Solvay ovens,Koppers ovens, etc., but will be more particularly described andillustrated in connection with by-product coke ovens of the Semet-Solvaytype.

Referring to the drawings, 5 indicates the coke oven having a pluralityof uptake pipes 6 connected to a collector main 7 from the centre box 8of which the gases and vapors are delivered through a cross-over main 9to the condensing system which includes condensers 10. The gases afterpassage through the condensers 10 may be delivered to anexhauster 11andthence to the usual equipment provided in coke-oven plants for therecovery of other valuable products from the gases. The goose-necks andcollector main may be provided with the usual spray nozzles 12 adaptedto be supplied through a pipe 13 with ammonia liquor or ammonia liquorand tar for the purpose of cooling the hot coke-oven gases. The tarwhich condenses and separates in the collector main can be withdrawnfrom the centre box through a pipe 14 and delivered to a decanter 15 inwhich the ammonia liquor is separated from the tar. The ammonia liquorcan be returned then to the spraynozzles for further use as a coolingagent. The tar'may be delivered to acollecting tank 16. The tar andammonia liquor which separate in the cross-over main can be withdrawnand delivered to a decanter 17 in which the ammonia liquor is separatedfrom the tar. The tar can be delivered to a collecting tank 18. The oilsseparated in the. condensers can be withdrawn and delivered to adecanter 19 in which the ammonia liquor is separated and the oils canthen be. delivered to a collectin tank 20. The structure and the mode 0operation thereof as hereinbefore described embody the usual structureand operation of a coke-oven battery with a by-product recovery system.c v

In accordance with the present invention one or more of the ovens of thebattery may be provided with stills 21 connected directly to the uptakepipes from selected ovens and to the collector main through suitablegoosenecks. The preferred form of still comprises a shell supported inany suitable way above the uptake pipe to which it is connected andhaving therein a plurality of spray nozzles 22 designed to introduce taror oil in the form of a spray. The spray nozzles may be connected bypipes 23 to one or both of the tar receptacles, pumps 24 being providedto permit the introduction of the tar under suitable pressure to ensurethe proper atomizing of the tar in the still. Annular collectors 25 aredisposed beneath each spray nozzle in the still and outlet pipes 26permit the withdrawal of the collected tar or pitch therefrom. The taror pitch so withdrawn can be delivered to receptacles therefor and re-.

turned if desired to the same or another level of the still toaccomplish the further distillation of the tar or pitch. A baflle 27 isdisposed preferably above the end of the u take pipe to prevent tar fromfalling into til oven and overflow pipes 28 are provided likewise. toavoid the possibility that accumulated pitch in the bottom of the stillwill overflow into the uptake pi e.

The still as described is connected through a goose-neck 29 to thecollector main near the, cross-over main so that the gases carryingvapors produced by the distillation are delivered to the collector mainand mingled with the gases from the remaining ovens of the battery.These gases pass then through the cross-over main to the condensingsystem where the vapors are condensed and separated in the mannerhereinbefore described.

In the operation of the a paratus the several stills are supplied wittar or oil produced either in the coke-oven battery or in anotherbattery and the tar or oil is subjected to the distilling eiiect of thehigh temperature gases from the coke ovens connected to the stills withthe result that volatile constituents-from the tar or oils are separatedand the gases flowing to the collector main are enriched. in condensableconstituents. The

' gasesthus utilized for distillation are, morea over, moreor lessfreedfrom tar particles by the scrubbing action of the tar sprays. If thegases from all of the ovens of the battery are thus utilized theresulting gases flowing from the collector main will be enriched veryconsiderably in oil vapors and the yield of oils therefrom will becorrespondingly increased. Furthermore, the oils will be cleaner oilsthan those usuall obtained from the condensers of a byre uct coke oven.

For t e reasons hereinbefore noted, it may be desirable in some cases toavoid mingling of these enriched gases with the gases from the remainderof the ovens of the battery,

- particularly where only afew of the ovens tional condensers32'designed to effect the.

progressive cooling of the gases to predetermined temperatures at whichthe desired oils will condense and separate so that they can bewithdrawn as separate products from the system. The gases remainin aftercondensation can be conveyed throng a pipe 33 to the exhauster 11 whichmaintains the pressure balance of the system.

By regulation of the temperature and operation of the stills and thecondensers connected thereto diflei'ent pitches and different types ofoils may be obtained.

While I have described-and illustrated a particular.type andconstruction of a still adapted to accomplish the purposes of theinvention, it will be evident that the invention in its broader aspectscan be carried out in an apparatus of modified construction in which thehot gases are employed in the manner described for the distillation oftar and the production of pitch and oil vapors therefrom.- Variouschanges can be made, there-' fore, in the details of operation and arranement of the apparatus without departing from the invention orsacrificing any of the advantages thereof.

I claim 1. The method of distilling tar, which comprises passing hotcoke-oven gases through successive sprays of coal tar immediately afterthe gases leave the ovens, thereby eflecting distillation of the tar,the first spray being subjected thereby to thg maximum temperature ofthe gases and each of the suc ceeding progressively decreasingtemperatures, and

sprays being subjected to gases of" separately collecting the residuefrom the distillation of the tar in the successive tar sprays.

2. The method of distilling tar, which comprisesplas'sing hot coke-ovengases upwardly throng I successive sprays of coal tar introduced atdifferent levels immediately after the gases leave the ovens, therebyeffecting distillation of the tar, the first spray being subjectedthereby to the maximum temperature of the gases and each of thesucceeding sprays being subjected to gases of progressively decreasingtemperatures, and separately collecting the residue from thedistillation of the tar in the successive tar sprays.

3. The method of distilling tar, which comprises passing hot coke-ovengases through successive sprays of coal tar introduced at differentlevels immediately after the gases leavethe ovens, thereby effectingdistillation of the tar, the tar introduced at the successive levelshaving different compositions adapted for distillation at theprogressively lower temperatures of the gases, and separately collectingthe residue from the distillation of the tar at the different levels.

4. The method of operating coke ovens,

which comprises forcing the gases'from part of the ovens immediatelyafter they leave the ovens, through successive sprays of-tar from otherovens arranged at progressively higher levels, drawing ofl' thedifferent pitches at the successive levels, passing the gases and vaporsresulting from the distillation to a condensing system separate fromthat employed for the gases not used for the distil lation of tar andrecovering condensable products therefrom.

In testimony whereof I aflix my signature.

STUART PARMELEE MILLER.

